Dual chamber airbag system

Abstract

A side airbag system for a vehicle has a primary airbag and a secondary airbag at least partially surrounding the primary airbag. The primary airbag comprises at least one primary vent venting into the secondary airbag and the secondary airbag comprises at least one secondary vent. The primary airbag is inflated by an inflator and the secondary airbag is inflated by gases leaving the primary airbag through the primary vent. The secondary airbag has a panel overlying the primary vent, and inflation of the primary airbag urges the vent and panel in an outboard direction against outboard vehicle structure to restrict flow through the vent. The inflation rates of the primary and secondary airbags are thereby controlled such that the primary airbag protects a vehicle occupant against impacts with a localized load profile and the primary and secondary airbags together protect the occupant against impacts with a distributed load profile.

What is claimed is: 
     
       1. Apparatus comprising:
 a seat for installation in a vehicle with an outboard side of the seat facing a vehicle side; 
 a primary airbag mounted to the outboard side of the seat and having a vent on an outboard-facing wall; and 
 a secondary airbag enclosing the primary airbag and having a panel overlying the vent, inflation of the primary airbag urging the vent and panel against the vehicle side, the panel restricting flow through the vent. 
 
     
     
       2. The apparatus of  claim 1 , wherein the primary airbag further comprises at least one second wall facing one of an upward and a downward direction, the second wall having at least one second vent thereon. 
     
     
       3. The apparatus of  claim 2 , wherein the second vent is located and the primary and secondary airbags are configured such that the secondary airbag substantially covers the second vent for a period of time during inflation prior to the primary airbag reaching full inflation. 
     
     
       4. The apparatus of  claim 2 , wherein at least one of the vent and the second vent comprises a tunnel through which gases leaving the primary airbag flow. 
     
     
       5. The apparatus of  claim 2 , wherein at least one of the vent and the second vent comprises a flap valve. 
     
     
       6. The apparatus of  claim 2 , wherein at least one of the vent and the second vent comprises a panel of woven fabric that permits venting through the fabric. 
     
     
       7. The apparatus of  claim 1 , wherein the secondary airbag substantially surrounds the primary airbag. 
     
     
       8. The apparatus of  claim 1 , wherein the secondary airbag is coupled to the primary airbag about an edge of the secondary airbag. 
     
     
       9. The apparatus of  claim 1 , wherein the secondary airbag has a secondary vent on a wall thereof, the secondary vent positioned such that no vent of the primary airbag vents directly into the secondary vent. 
     
     
       10. The apparatus of  claim 1 , wherein the secondary airbag occupies a volume less than a volume of the primary airbag when in a fully inflated state. 
     
     
       11. A side airbag system for a vehicle, comprising:
 a primary airbag having a vent on an outboard-facing wall thereof; and 
 a secondary airbag enclosing the primary airbag and having a panel covering the vent, whereby inflation of the primary airbag urges the vent and panel in an outboard direction and against vehicle structure, the panel restricting flow through the vent. 
 
     
     
       12. The side airbag system of  claim 11 , wherein the primary airbag further comprises at least one second wall facing one of an upward and a downward direction, the second wall having at least one second vent thereon. 
     
     
       13. The side airbag system of  claim 12 , wherein the second vent is located and the primary and secondary airbags are configured such that the secondary airbag substantially covers the second vent for a period of time during inflation prior to the primary airbag reaching full inflation. 
     
     
       14. The side airbag system of  claim 12 , wherein at least one of the vent and the second vent comprises a tunnel through which gases leaving the primary airbag flow. 
     
     
       15. The side airbag system of  claim 12 , wherein at least one of the vent and the second vent comprises a flap valve. 
     
     
       16. The side airbag system of  claim 12 , wherein at least one of the vent and the second vent comprises a panel of woven fabric that permits venting through the fabric. 
     
     
       17. The side airbag system of  claim 11 , wherein the secondary airbag substantially surrounds the primary airbag. 
     
     
       18. The side airbag system of  claim 11 , wherein the secondary airbag is coupled to the primary airbag about an edge of the secondary airbag. 
     
     
       19. The side airbag system of  claim 11 , wherein the secondary airbag has a secondary vent on a wall thereof, the secondary vent positioned such that no vent of the primary airbag vents directly into the secondary vent. 
     
     
       20. The side airbag system of  claim 11 , wherein the secondary airbag occupies a volume less than a volume of the primary airbag when in a fully inflated state.